This invention relates generally to popcorn poppers and more specifically to a automatic or manual popcorn poppers which produce popcorn in consecutive batches while reducing the amount of attention required from an operator and while producing a consistently high quality of popped corn. This invention also relates to an improved method for popping popcorn.
Popcorn is mass-produced for sale at movies and other events in commercial popcorn poppers which include an enclosed, transparent cabinet containing a tiltable kettle suspended above a catch area or platform. The kettle is heated and uncooked popcorn kernels are placed therein to be cooked and popped. Once the kernels are popped, the kettle is manually tilted and the popcorn spills onto the platform to be scooped up, packaged and sold to customers.
Conventionally, commercial popcorn poppers have been manually operated and have required an operator""s constant attention for cooking the kernels and subsequently dumping the popped popcorn. For example, an operator would load the kettle with popping oil and unpopped corn kernels and then listen and watch for the unpopped corn to pop. When the operator decided, somewhat arbitrarily, that the corn was sufficiently popped, they would then dump the kettle and spill the popcorn onto the serving platform. Additional oil and corn would then be added for the next batch. While such conventional popcorn poppers are generally effective in mass-producing popcorn; the constant attention they require prevents the operator from other important tasks, such as selling the popcorn and other concession products, taking money and generally servicing customers.
As may be appreciated, the multiple duties entrusted concessionaire operators are not conducive to having them constantly monitor a popcorn popper. If attention is diverted for an extended length of time, the popcorn is susceptible to being burned or overcooked. In addition to the waste of burned popcorn, the aroma of the burned popcorn is not attractive to customers and may actually discourage purchases. Furthermore, if the operator inadvertently dumps the burned corn onto the platform, it will contaminate the usable popcorn which has already been produced and may render the entire batch inedible and thus unusable. Still further, the results and mess from burned popcorn is not easy to clean. The kettle is hot and must be allowed to cool before the burned popcorn is removed and the kettle placed back in service.
Additionally, the arbitrary nature of the dumping process with conventional poppers makes them subject to messes associated with premature dumping. For example, if the operator mistakenly believes that the corn has been completely popped and the oil used when indeed uncooked corn and oil remains in the kettle, tilting the kettle will spill oil onto the serving platform and possibly onto the counter. Such spills ruin and waste popcorn and create a mess which must be cleaned, adding to the already numerous tasks of a concessionaire.
Still further, too much oil may be added for a particular cooking cycle, and even if the cooking cycle is completed, excess oil might be left, again resulting in a mess upon dumping of the batch. For example, one operator may load the uncooked corn and oil for a batch, and another operator may subsequently and inadvertently load more oil, believing it had not been added. The excess oil does not burn off or cook and remains in the kettle. Not only is a mess created upon dumping, but the excess oil may also foul the batch of popcorn.
Another drawback of conventional popcorn poppers is the inherent delays which will occur between cooked batches of popcorn. When the popcorn has been cooked and dumped, the operator may begin serving it to customers without replenishing the supply of corn and oil and starting the next batch. Therefore, the next batch of popcorn will not be produced until the operator consciously sets aside time from his other activities to do so. Such delays interrupt production rates and introduce inefficiencies into the operation which reduce popcorn sales.
It is also desirable to pop popcorn consistently so that it produces high quality consistent taste from batch to batch. The vagaries of prior systems leave much to chance in this regard so that batches of corn are undercooked, burned or the like and at the least are inconsistent in taste.
Still another but related drawback to conventional popping processes or mechanisms is that they sometimes provide inconsistent or improper heating of the popcorn so that proper expansion of the kernels upon popping is not achieved. Particularly, when the heat is too high, the steam from the kernel is prematurely forced out and the popped kernel is small. If the temperature is too low, the kernels do not experience proper hull expansion and brittleness at popping and the popped kernels are small. It will also be appreciated that small popcorn kernels reduce the yield of popped popcorn per unit of uncooked kernels, thus reducing the efficiency of the popping apparatus and raising the cost of the operation.
While one aspect of the invention herein lends itself to reduction of the vagaries of operational and processing circumstances as noted above, it is also noted that it is important for an operator to tend to the process at specific times, yet remaining free to handle other chores while the popping process is processing. For example, in many popping systems, it is desirable and even necessary for an operator to tend to loading the kettle with corn and oil for popping at an appropriate time in the cycle. It is also desirable for an operator to monitor or to cause dumping of popped corn from the kettle at a particular time to keep it from burning. Yet it is also desirable both that the popping process does not fully engage the operator doing the whole process and that his attention to the process is positively obtained at such times as loading and dumping.
In another aspect of the invention, it is recognized that in the past, various improvements in popcorn have been made by popcorn producers in the science and technology of the corn. These have resulted in improved taste, improved kernel expansion rates and more complete popping. Improvement in the popping machines or equipment to produce better popped products have not generally kept pace with the improvements in the corn. While there have been certain improvements in poppers directed to better popped corn products, such as in U.S. Pat. Nos. 5,743,172; 5,694,830 and 5,871,792, for example, there is still room for further equipment and process improvement to improve the final popcorn product.
In particular and as referred to above, it should be appreciated that popped popcorn should not be chewy, should have a high expansion ratio from the unpopped kernel, and should have about 12% to about 13% of the moisture of the raw, unpopped kernel. Popcorn meeting these parameters is highly desirable from a taste standpoint. Despite improvements in the corn kernels, however, these final desirable parameters require improvements in popping technology for consistency.
For example, if the moisture content of the kernel is reduced too fast in the popping process, the kernel pops prematurely, resulting in a small product. On the other hand, if the moisture content of the kernel is reduced too slowly, the hull first cracks, moisture leaks and the power of the remaining moisture is not sufficient to produce the desired expansion of the kernel for the final product. Thus the rate of application of heat to the corn is a factor in producing the most desirable popcorn.
In a typical popper, a covered heated popping kettle is generally used. Heating elements are usually mounted on the underside of the kettle and are controlled by a mechanical thermometer between on/off status to heat and pop the corn therein. In one instance, a thermocouple has been used. The elements are disposed on a heat dissipation plate or surface on the kettle bottom and have sufficient output to heat the kettle to a level in excess of the ultimate temperature desired after popcorn kernels and oil are loaded (which reduces kettle temperature from a control or preset temperature). The elements produce such excess heat in order to ensure that the appropriate popping temperature can be reached is a desired time period.
In other words, when relatively colder corn and oil are added to a heated kettle, the temperature drops, then climbs back to a desired temperature so that the kernels are exposed to a quantum of heat during a period necessary for popping. If the elements were not so powerful, the desired heat may eventually be attained but this could require an excessive duration of cooking time.
The graph in FIG. 8 of U.S. Pat. No. 5,871,792 demonstrates such a popping cycle. From a cold start with the kettle at an ambient temperature, the heating elements are turned on to warm the kettle. Its temperature rises to an xe2x80x9covershootxe2x80x9d level above a xe2x80x9ccontrolxe2x80x9d level of about 525xc2x0 F. The heating elements are then cycled on and off upon sensing by a mechanical thermometer so that kettle temperature cycles above and below the control temperature.
When the unpopped kernels and oil are loaded into the kettle, they are at ambient temperatures, much cooler than the kettle""s control temperature, and act as a heat sink, thus reducing the kettle temperature, such as shown in the graph, down to about 325xc2x0, for example. The mechanical thermometer, for example, eventually sensing this drop, causes the heating elements to energize to raise the kettle temperature back up toward a temperature where the corn is considered to have been popped and can be dumped.
There are several areas in which this process could stand further improvement as will now be discussed.
Applicant has determined that an ideal cooking time of from about 3.0 minutes to about 3.5 minutes is preferred in order to produce the best tasting popcorn with the highest expansion ratio (largest size). Achievement of this ideal process requires close control of the heat energy of the kettle. If the initial heat energy of the kettle (i.e. considering kettle temperature and kettle mass) and/or the ability to recover after the corn and oil is loaded (i.e. considering temperature, mass and available wattage of heating elements) is too low or too high, the cooking cycle will be too slow or too fast respectively. When the cooking cycle is too slow or too fast, the popcorn will be too small, chewy and will have too many unpopped kernels.
Moreover, when the popping is first heated from a xe2x80x9ccold startxe2x80x9d, on initial turn on, its temperature rise may be rapid, causing it to overshoot and reaching a higher temperature than initially desired. While controllers such as that disclosed in the aforementioned patents cited herein are useful in eliminating excessive overshoot in subsequent cycles, they have not been so advantageous for the initial cold start cycle or the first several popping cycles thereafter before the cooking system reaches a heating equilibrium. This can cause undesirable taste and quality variations in the initial popped corn batches.
In order to fully understand the cooking process and as background for the invention herein, it is helpful to articulate certain definitions, functions and structure of popcorn poppers. Generally, the kettle is as explained above and includes a covered heated kettle provided with heating elements for heating a heat dissipation plate or surface on the kettle bottom, and thus the kettle.
Based on the kettle construction, its mass, the materials of the kettle, etc. the power of the heat elements (watts) are determined to permit the kettle to recover from the temperature drop resulting from loading of the corn and oil. Then, one of the significant remaining variables is the temperature of the kettle, which determines the initial heat energy of the kettle. Thus, the xe2x80x9ccontrol temperaturexe2x80x9d (Tcontrol) means a preselected temperature of the cooking or popping surface of the kettle, which the controlling method or apparatus allows the kettle to approach before it is shut off in the first cycle from a cold start. The xe2x80x9cload temperaturexe2x80x9d (Tload) means the preferred temperature of the cook or popping surface of the kettle at the time when corn kernels and oil is loaded into the kettle before the temperature drop. The xe2x80x9cdump temperaturexe2x80x9d (Tdump) means the predetermined temperature of the cook or popping surface of the kettle when the corn has popped and the kettle is ready for dumping the popped corn. Typically in current poppers, Tload is greater than Tdump by a small percentage.
According to the invention, applicant has determined it is desired to produce enough heat in the corn to cause it to be popped when the kettle reaches a predetermined ump temperature at about 3.0 to 3.5 minutes after the kettle is loaded. Thus, according to the invention, the kettle should be controlled in each cycle such that a predetermined Tdump is reached within the ideal cycle time of about 3.0 minutes to about 3.5 minutes from the loading of kernels and oil to dumping of popped corn. This appears to produce the most consistently high quality, good tasting popcorn, the process of the invention disclosed herein is directed to reaching a predetermined and constant Tdump temperature for all situations. The potential variations of cooking time based on varying Tload temperature points are shown in the following graphs. These show the relationship of varied Tload temperatures and the initial heat energy of the kettle to the popping cycle in time.
FIG. 9 illustrates a situation where Tload is equal to Tdump. FIG. 10 illustrates a situation where Tload is greater than Tdump. FIG. 11 illustrates a situation where Tload is less than Tdump.
From these graphical illustrations, the following observations can be made:
First, the overall slopes of the curves are similar, just shifted up or down. This is because all three graphs assume the same heating elements and wattage, and the same kettle construction and mass.
Secondly, the popcorn has completed popping at the same Tdump temperature, independent of the Tload temperature of the kettle when the corn is loaded. This observation will be described later as one of the important concepts contemplated by the invention.
Thirdly, the loading of corn and oil at different Tload temperature extend or shorten respectively the duration of the cycle until reaching Tdump. This inconsistency of Tload most frequently occurs between the first or cold start cycle and the subsequent cycles. If kernels and oil are added at that time, i.e. a high Tload temperature, then the cycle time or duration may be too short. If the kernels and oil are added at a lower Tload temperature, too much before Tcontrol is reached, then the cycle time is extended beyond that time duration desired.
It will also be appreciated that varying xe2x80x9clagxe2x80x9d factors are inherent in prior poppers, and that these lag factors prevent the close control of kettle energy now desired and which is provided by the invention herein.
Thus, if the Tcontrol temperature and the Tload temperature are maintained as closely as possible according to the invention, then the cycle duration can be more closely or accurately produced within the desired cycle time of about 3.0 to about 3.5 minutes.
Given the importance of keeping the Tload temperature substantially equal or as close to the Tdump temperature as possible for the best quality popcorn according to this invention, the challenge is to minimize the normal differences between heat energy imparted to the corn for the first cold start cycle and for the subsequent cycles. The differences can occur due to at least the following circumstances:
a. The point where the temperature sensor is located is separated from the cooking surface. This is related to the mass of the materials between the temperature sensor located on one hand and the cooking surface. The effect is a time and temperature lag between what the cooking surface temperature actually is, and what the remote temperature sensor and control xe2x80x9cthinksxe2x80x9d it is.
b. The surface where the heat elements are located is separated from the cooking surface by the kettle components, which also introduces a time and temperature lag. When the heat element is turned on or off, there is a lag before the cooking surface begins to react. There is also a small lag associated with the heat element itself. Thus the mass of material between the heating element and the actual cooking surface, as well as the rise time of the heat element itself involves an inherent temperature and time lag.
c. The traditional method of controlling temperature of a popcorn kettle which is by use of a xe2x80x9cmechanicalxe2x80x9d thermostat, inaccuracy aside, or even a thermocouple with a set or nonprogrammable control inherent introduces its own time lag related to the mass and mechanical operation of such a sensor.
d. And perhaps most importantly, the fact that if the cold start cycle is controlled the same way as subsequent cycles, the initial Tload may be too low and the duration of that cycle, until Tdump is reached could be too long.
The various factors described above are amplified by the fact that the kettle""s heat elements usually have far more power than is necessary to simply hold the kettle at a Tcontrol or Tload temperature. This is necessary to cook the popcorn in the required time, i.e. to bring up the temperature of the corn for popping in a desired time. With the lag times of many prior poppers, the net effect is a large overshoot of preferred control temperature as the kettle at least initially heats or an undershoot if the heat energy is turned off too soon because of an excessive sensed rise rate. By the time the mechanical thermostat or thermocouple reacts to turn off the heat, the kettle surface temperature could exceed Tcontrol by the overshoot. Also, even where a thermocouple is used, its own heat equilibrium may not be obtained during the first or first several cooking cycles and the accuracy and dose control of the cooking process desired is not initially obtained. Conversely, before the heat element turns on, the temperature will undershoot. The chart of FIG. 12 demonstrates this operation.
The thermal transients in the system are believed to be one of the most significant of the factors generating this prior profile in those systems using such sensors. As mentioned above, there are two major problems with temperature sensors related to the effects described.
First, overshoot from a cold start. The operator does not know when to load the corn and oil from a cold start. If he puts the kernels and oil in too early, the quality of the popped corn will be poor. If he waits too long, he may xe2x80x9chitxe2x80x9d the peak overshoot temperature which will also cause poor quality popped corn and may cause oil smoke.
When the PID controls heat rise from a cold start, the heat energy may be turned off too soon, but the lack of heat equilibrium results in less heat energy in the system and too long or time is required for the kettle to recover to Tdump after its first load.
Secondly, excessive popping cycle times due to low (and also due to high) kettle temperatures are undesirable. The low condition is obvious, but a high load temperature actually can cause lengthy popping cycles up to 5 minutes. The kettle""s temperature sensor opens due to a high temperature. The overshoot permits the heat energy of the kettle to increase further. If the corn and oil are added at this time, the heat energy of the system falls quickly, but the higher sensed surface heat from the overshoot xe2x80x9cfeedsxe2x80x9d the remote mechanical thermostat or thermocouple which keeps it from closing. By the time the heat energy in the kettle mass between the cooking surface and the remote sensor dissipates and the sensor does close and the heat elements are turned on, the kettle cannot recover to cook the popcorn close to the desired cycle time.
Accordingly, it is desired to produce a consistently higher quality popcorn through improved apparatus and popping processes.
Another objective of the invention has been to reduce popping kettle temperature overshoots and undershoots as a function of system parameters of prior popping systems.
Another objective of the invention has been to provide a consistently higher quality popped corn by more closely controlling the popping parameters of the corn poppers than in prior systems.
A yet further objective has been to overcome the information and problems generated by application of the control logic to both cold start and subsequent popping cycles.
A yet further objective of the invention has been to provide improved popped corn by insuring a consistent popping cycle within the duration of about 3.0 to about 3.5 minutes independently of the coincidence of the loading of kernel and oil with the temperature (Tload) for all cycles of the popper.
It is another objective of the present invention to provide improved apparatus and/or methods to pop popcorn continuously in consecutive batches with minimal attention by an operator.
It is another objective to ensure that the popcorn is consistently and properly cooked in each batch.
It is a further objective of the present invention to reduce the burning of popcorn sometimes associated with conventional machines and operator inattention.
It is also an objective of the invention to always provide the proper amount of cooking oil and thus reduce the messes associated with such burned popcorn or spilled, uncooked oil and thereby allow an operator to focus upon customers and popcorn sales.
It is a still further objective of the invention to reduce the delays between fresh batches of popcorn attributable to lack of attention by the operator.
It is a still further objective of the invention to increase the production rate of consecutive batches of fresh popcorn to thereby increase the sales from and the profitability of a commercial popcorn popper.
Still further, it is an objective to provide the proper and consistent heat to the kernels as they cook to ensure proper popping conditions and to maximize the popcorn yield per unit of kernels.
Addressing these objectives, the present invention comprises a popcorn popper which may be left unattended to automatically cook and dump popcorn once it has been loaded with the proper ingredients, such as uncooked popcorn. Alternately, features of the invention are also applicable to poppers with manually dumped kettles. The proper, premeasured amount of oil pump is then added by the oil pump system upon the initiation of a cooking cycle so that the operator does not have to worry about measuring oil or excess oil in the kettle. The popcorn popper of the invention is responsive to kettle temperature conditions to automatically cook popcorn kernels, subsequently dump the finished popcorn, and then alert the operator to load more ingredients such as oil and uncooked kernels, and start the next batch. In that way, all of the batches of fresh popcorn are properly cooked at regular periods with the proper amount of oil and heat, and the operator is left to attend to other tasks.
According to the invention, popcorn is consistently cooked by introducing an amount of popcorn and oil to a cooking system, comprising a heated kettle, for a duration sufficient to heat the corn and oil a predetermined amount, and then automatically dumping popped popcorn after a sufficient amount of heat energy has been absorbed by the corn and the oil to pop the corn. The application of heat energy to the corn and oil is not monitored and controlled by time, but rather by the heat conditions of the cooking system for each batch. In this regard, a kettle is heated to a start temperature and cycled about that temperature through a small temperature range. When unpopped corn and oil are introduced, a thermocouple on the kettle senses a temperature drop (cycle point) and a cooking or popping cycle begins. The corn and oil absorb the heat energy and are heated in the kettle until the kettle temperature climbs back to a predetermined temperature (dump point) indicating sufficient heat energy has been applied to the corn and oil to pop the corn. At that point, the kettle is automatically dumped.
Since the controller is temperature, rather then time responsive, the operator is assured a consistent amount of heat is always applied to the corn and oil for consistent popping. If the kettle dump was controlled by time alone, and the environment changed, such as a cabinet door being open, the cooking cycle might time out before sufficient heat energy was applied to consistently cook that batch of corn. Moreover, since the start temperature is held within a narrow predetermined range, the oil and corn will not be prematurely burned and the temperature gradients applied thereto will be more consistent. Also, such a method accommodates at least some variations in the amount of corn and oil introduced to the kettle. If too little, the temperature drop will not be as great and the rise to the predetermined dump temperatures takes a shorter time, thus sufficient but less heat is introduced so this batch is consistently popped. In a corresponding manner, larger amounts of corn and oil will slow the climb of temperature to the dump point insuring that sufficient heat is imparted to pop the corn consistently with other batches.
To further ensure proper cooking by the invention, a premeasured amount of oil is introduced to the kettle at the beginning of a cooking cycle. The controller is coupled to an oil pump system which is operably in fluid communication with the kettle. Upon the kettle reaching the proper start temperature or cooking temperature, the oil pump system and an oil pump switch are enabled. The operator then actuates the oil pump switch to activate the pump system and deliver a proper, premeasured amount of oil to the kettle. The oil pump system and switch are disabled by the controller if the kettle heat is not ON (no cooking cycle) or the kettle is tilted from an upright position, such as to be cleaned. Furthermore, in accordance with the principles of the present invention, the oil pump system will only deliver one load of oil per cooking cycle to prevent an oil overload or spilling of oil when the cooked batch of popcorn is dumped. Therefore, the oil pump switch may be actuated numerous times and only one load of oil will be delivered per cooking cycle.
In an alternative embodiment of the invention, the controller is operable to activate the oil pump system automatically upon the initiation of a cooking cycle. To that end, the controller provides an output signal to the oil pump system to pump a premeasured amount of oil to the kettle at a predetermined time in the cooking cycle. For example, the oil might be added when the kettle has risen to a start temperature or might be added after the popcorn has been added. If the oil pump system has a mechanically adjusted timer mechanism for pumping a premeasured amount, an output signal is provided by the controller to activate the pump and pump oil into the kettle. If the oil pump system includes a programmable timer mechanism, the controller is operable to provide additional timer outputs to adjust the amount of time that the pump will deliver oil when activated. In either case, a premeasured and proper amount of oil is delivered to the kettle each cooking cycle. The controller will not activate the pump system until the kettle is hot and ready to cook and is upright.
More specifically, the popper apparatus includes a kettle which is coupled to a dumping motor and a heater which are controlled by a controller which monitors the kettle temperature. The controller includes a temperature sensor, such as a thermocouple, which is operably connected to the kettle proximate the heaters. By monitoring the temperature of the kettle, the controller is operable to dump the kettle at the proper time and to alert the operator when another batch of uncooked corn kernels should be added to the kettle. Since the kettle temperature is constantly monitored, and the dump cycle is automatically controlled, the burning of popcorn is prevented. Furthermore, an operator does not have to constantly monitor the procedure to prevent such burning and can thus turn his attention to other tasks. The popper begins a cooking or popping cycle when fresh ingredients are added, and by alerting the operator at the end of each popping cycle, the popper effectively reduces the delay between batches to increase its productivity.
In a preferred embodiment of the invention, a programmable logic controller (PLC) is coupled to a temperature controller which, in turn, is coupled to a kettle thermocouple and to kettle heaters. When the popper is turned ON and the kettle heat is turned ON, the kettle is heated to an equilibrium start or cooking temperature of, for example, approximately 525xc2x0 F. The thermocouple and temperature controller preferably maintain the desired 525xc2x0 F. kettle cooking temperature in a small cycled range of +/xe2x88x9210xc2x0 F. When the kettle has reached the equilibrium start temperature, the PLC activates indicators which provide visual and audible indications that the kettle is ready to make popcorn. The oil pump system and pump switch are enabled and the operator actuates the oil pump switch to load the oil which is pumped in by the oil pump, and also loads the uncooked popcorn kernels.
Alternatively, the oil might be loaded by hand by the operator. In still another alternative embodiment of the invention, as discussed above, the PLC provides outputs directly to the oil pump system to automatically pump oil to the kettle at the initiation of a cooking cycle. The PLC is operably coupled to the oil pump system to activate the pump for a predetermined amount of time to ensure a premeasured amount of oil. A timer determines how long the pump runs once activated to ensure the proper amount of oil. The invention may incorporate an oil pump system having a mechanically adjusted timer, such as a dial timer, or may incorporate a system having a separate programmable timer. In the latter case, the PLC is operable to provide separate output signals to the programmable timer to set the pump time in addition to any output signals to the pump for delivering oil for the amount of time set by the timer.
The temperature controller senses the rapid drop in kettle temperature associated with the absorption of heat from the kettle by the corn and oil. When the temperature drop exceeds a set amount, for example, 50xc2x0 F. below the equilibrium start temperature, the PLC initiates a cooking cycle. The point of initiation of the cooking cycle is designated the cycle temperature or cycle point.
As the cooking cycle progresses, the PLC senses through the temperature controller, that the kettle has dropped to a minimum temperature below the cycle temperature. The minimum temperature will depend upon the heat load added to the kettle. As the popcorn pops, the temperature of the kettle begins to rise above the minimum temperature. When the kettle temperature reaches a predetermined dump temperature or dump point and the PLC that the minimum temperature was previously reached and was preceded by the cycle temperature, the popper indicates that the end of the cooking cycle has occurred. Preferably, the predetermined kettle dump temperature associated with the dump point for determining the end of a cooking cycle is equal to the cycle temperature associated with the start of the cooking cycle, i.e., approximately 50xc2x0 F. below the equilibrium start temperature, for example. Upon sensing the end of the cooking cycle at the dump point, the PLC initiates a dump cycle and controllably energizes the dump motors to tilt the kettle and dump the finished popcorn onto the surface platform. The popcorn is immediately and automatically dumped at the end of a proper cooking cycle, therefore preventing the popcorn from burning. Furthermore, because of the unique temperature-driven control of the popper, the popcorn is consistently and properly cooked and may be served at the peak of freshness. The greater the amount of corn and oil added, the longer the cooking cycle. Conversely, the less the amount of corn and oil, the shorter the cooking cycle.
Preferably, the motors are controlled to dump the kettle twice to ensure complete dumping. After the first dump, the kettle is only partially returned to a cooking or popping position. It is then dumped again before fully returning to a popping position.
When the temperature controller indicates that the kettle temperature is below the cooking cycle point and the machine is in a cooking cycle, the PLC disables the dump motors and thus prevents inadvertent dumping of the kettle contents.
When the popcorn has been dumped at the end of a cooking cycle, the kettle will heat back up to the start cook point again, and audible and visual indications are again initiated to remind a busy operator to reload the kettle with fresh ingredients. This prevents delays in between consecutive batches of popcorn and thus increases the efficiency of the operator and the popcorn popper, increasing production rates and profitability.
The present invention provides the proper application of heat energy consistently to batches of corn kernels. In that way, the kernels are heated to a sufficient temperature to provide proper hull brittleness and expansion when the kernels pop but the heat is not so high so as to force out the steam in the kernel prematurely. Therefore, the invention achieves the desired corn temperature and peak steam pressure for proper expansion. Expansion rates of approximately 1:50 have been achieved with the invention which is a significant improvement over some conventional devices which achieve expansion rates of 1:44 or lower.
Therefore, the present invention automates the cooking and dumping of popcorn and eliminates the need for constant operator attention to the process. Production of consistently popped corn is increased as is the profitability of the operation while incidents of burned corn and inadvertently spilled oil or uncooked corn are eliminated. Furthermore, the temperature control of the kettle operation and the cooking cycle provides properly and consistently cooked batches of popcorn.
An alternative embodiment of the invention contemplates the use of a kettle-mounted thermocouple interconnected to an electronic control system for operating the kettle""s heating elements, and a different control logic for the first heat rise of the kettle from a cold start condition. The thermocouple has negligible mass, is located on the bottom of the kettle, and is connected to the electronic control which will control voltage to the heat elements, depending on the desired thermocouple open and close temperatures. The overshoot and undershoot will thus be significantly less due to the elimination of some lag due to the use of remote mechanical thermostats in prior systems. Moreover, the control system is programmed to energize and deenergize the heating elements in response to the sensing conditions of the thermocouple at temperatures which lead to the desired cook surface temperatures as a function of kettle mass and heating element lags in both directions (i.e. temperature rises and drops). Thus, the thermocouple sensed temperatures are handled by the control system as a function of the desired temperatures taking into consideration kettle mass and other lag factors so the heat energy that the corn kernels experience is closely controlled to predetermined levels.
The cold start problems noted above are prevented by directly controlling the application of heat to the kettle on the start up, outside of the normal control loop. In particular, heat energy input is not retarded or controlled so quickly as it is later when the structure has reached heat equilibrium. Thus, the program for normal operation is varied for the first cycle to insure that batch is consistently popped within the desired time frame as subsequent batches. The system then returns to normal control mode. Thus, the control system recognizes the cold start situation for the first cycle.
In other words, on cold start, the control system logic for remaining cycles is not applied to the kettle heat. Instead, the temperature rise is allowed to continue to a point beyond where it would be allowed to rise for subsequent cycles when the kettle has reached equilibrium. In this manner, the kettle is allowed to heat to a higher point, recognizing that total heat in the system is less than it will be later. Thus, when corn and oil are added and the temperature drops, the higher start temperature supports the kettle""s recovery to a Tdump temperature in a similar time frame to that of subsequent cycles. Without the xe2x80x9coverridexe2x80x9d of the control logic for the first cold start cycle, the heat energy would be retarded sooner and corn loading would drop the colder kettle to a much lower temperature than desired, from where it could take an excessive time to recover.
The chart of FIG. 13 illustrates the contrast between the invention and the prior systems.
It will be appreciated that Tdump, according to the invention, is constant and independent of Tload. According to the invention, Tdump is independent of many other variables, including:
Low voltage, which reduces the power of the heat elements.
Variations in the amount of corn and/or oil that are added to the kettle.
Variations in the kettle components: heat elements, etc.
The system is thus controlled that, given the same Tdump, temperature popping time will vary only within the desired cycle time of about 3.0 to about 3.5 minutes for every cycle.
In another aspect of the invention, and even where an automatic dump mode is or is not selected, or in other poppers where there is no automatic dump mode, the electronic control system is operable to sound audible or visual alarms, such as a buzzer or flashing light, to alert the operator to dump the popcorn at the correct time. Also, such alarms are programmed to alert the operator to do one of the following three things according to the invention:
1. From a cold start, an alarm signals when the operator should first add the corn and oil.
2. When popping, an alarm signals when to dump the popcorn. The larger benefit is the fact that it alerts the operator, who is busy or distracted, to dump the popcorn before it burns. Burned popcorn is a significant problem in a busy theatre, for example.
3. When the operator is done popping corn, an alarm reminds him to turn off the master power to the kettle heat to save energy.
The invention also contemplates the process of producing popcorn by popping corn kernels in oil for a time period of about 3.0 to about 3.5 minutes from loading kernels and oil into a popping kettle to dumping popped corn therefrom. That is, the invention contemplates the popping of popcorn in a time duration from loading kernals and oil into a kettle to dumping popped corn therefrom in a time period of from about 3.0 to abut 3.5 minutes and after a set Tdump temperature is reached, regardless of typical variations in the quality of corn and oil added by operator error and variations in the Tload temperature between cold start and later cycles.
According to the invention, a preset Tcontrol temperature thus defines a maximum Tload for the first cold start cycle and thereafter for subsequent cycles, function as a safety or cutoff temperature, causing a system shutdown when reached for review and safety considerations.
Advantages of the invention are numerous. It produces a high quality, consistent, popped product. It eliminates lag times of the prior temperature sensors used in prior popping systems. It reduces temperature overshoots and undershoots from a desired control temperature. It assures a predetermined cycle time within a set range and with a consistent product. It produces a high quality consistent product independent of variables inherent in prior systems which limit product consistency. It provides a close control of popping parameters, including close control of kettle energy to produce a non-consistently high quality product.
It will also be appreciated that the invention in its alternate embodiment can be used in controlling only the initial cold start cycle differently from the subsequent cycles or the first several cycles from a cold start in the same way, differently from remaining cycles when heat equilibrium is reached.
These and other objectives and advantages will become readily apparent from the following detailed description of preferred and alternative embodiments of the invention, and from the drawings in which: